Heat treating furnace



Dec. 12, 1933.

H. A. DREFFEIN HEAT TREATING FURNACE Filed Nov.

28, 1930 6 Sheets-Sheet 2 Dec. l2, 1933. H, A. DREFFEIN 1,938,814

HEAT TREAT ING FURNACE Filed NOV. 28, 1930 6 Sheets-Sheet 3 H. A. DREFFEIN 1,938,814

HEAT TREATING FURNACE Filed Nov. 28, 1930 e sheets-sheet 4 Dec. 12, 1,933.

EE EEEE www Dec. 12, 1933. A, DREFFEIN 1,938,814

HEAT TREATING FURNACE Filed Nov. 28. 1930 6 Sheets-Sheet 5 D 12 1933 H. A. DREFFEIN HEAT TREATING FURNACE e sheets-sheet 'e Filed Nov. 28. 1930 @Maa Patented Dec.12, 1933 UNiT-ED STATES PATENT OFFICE i HEAT TREATING VFUR/NACE I IHenryA. Dreffein, Chicago, Ill.1

v Application November 28, 1930 Serial No. 498,669

9 claims. (ci. 263-8) effect normalizing thereof with subsequent rapid cooling in a reducing or non-oxidizing atmos phere.

Another object is to provide a furnace for heat treating metal `sheets or thev like, as, for example, to a temperature which will effect normalizing, vand thereafter quicklyV and satisfactorily cooling the same in a minimum of time in a reducing or non-oxidizing atmosphere.l

Another object consists in the provision of a furnace with` improved combustion and heat supplying means; in the provision of such a fumacelin; which the flow of the heating gases is toward the charging end of the furnace; theprovision of such a furnace with a cooling chamber extension in which cooled products of com'- .bustion are utilized to accelerate the cooling of the metal sheets, or the like; the provision of such a furnace in which the cooling gases are utilized to ballie or obstruct the flow cf hot gases from'y the heating chamber into the cooling chamber; and the provision of means to contribute Vto the cooling ofthe metal sheets in the cooling chamber and simultaneously to preheat the air utilized for combustion of the fuel in the heating furnace. 1

Other objects reside in the details `of the structure hereinafter described in the following Y specification and illustrated in the accompanying drawings, in which 1' Figs.` 1a, 1b and 11c1are a horizontal section of the entire furnace structure;

Figs. 2a and. 2b are a vertical section of said furnace, an intermediate portion thereof being omittedfor convenience; 1 1 1 Y Fig.1 3l is avertical section 1along the line 3 3 of Fig. 1b; i Y 1 Fig. 411 is a similar section along the line 4-,4 of Figs. la and 2a; i

Fig. 5 rs avertical section *along the line 5 5 `ofFig.1c; 1

Figt 6 is a similar section along the line 6 6 of Figrlc. 11 1 numerals refer to like elements through-1 out the drawings.v i 1 l InFigs.-11a and 1b are illustrated in horizontal section the major portion'of the heating chamber of the furnace structure generally indicated by numeral 10, the same extending to the restrictingbaflle 11 (see Figs. .1c and-2b), at which point begins 1the coolingchamber, generally designated by numeral 12. The walls and floor of the heating and `cooling chambers are formed of suitable refractory, there Vbeing slots 14 in the floor of 1the chambers to permit the passage of conveyer members for the continuous conveynace. chamber `20 and the products of combustion flow Vtherefrom through the ports 23 adjacent the roof of the furnace structure, transversely ofV ance of metal sheets, or theV like, through the furnace structure.` At theentrance or 'charging end of the heating chamber is` providedy a vertically adjustable door 16 (see Fig. 2a) and 'simi` larly there is provided an adjustable door 17 at the discharge enclof the furnace (see Fig.v 2b).

I have found it expedient and desirable to use for heat generation and supply the invention disclosed in my. Patent No. 1,779,964 issuedOctober 28, Y1930, although I do not wish to be re#v stricted to the specific'combustion units except y as limited to details thereof by the claims. At`

one side `of the heating chamber adjacent the" charging end thereof the wall is offset at 18 to accommodate ay burner 19 into and through which I introduce at substantial velocity an ad'-` mixture of fuel and air, such as producerjgas and/air. Opposed to the burner 19 and spacedtherefrom is a restricted chamber 20, formed by the wall 21, there being a gap 22 between one end of said wall and the offsetfurnace wall 18.

At the top of the wall 21 are ports or passages" 23 (See Fig. 2a.) formed by the partitions 23a extending upward from the top of the wall 21.1`

These partitions 23a are inclined in such wise as to direct the gases flowing out ofthe chamber" 20 into the heating chamber proper partially toward the entrance end of the heating furnace.

The restricted chamber 20 is terminated at the j end opposed to the burner 19 by the Wall 25, at"

the opposite side of which is another restricted chamber 27 formedrby a partition wall 28 havingy partitions 28a extending upward from the wall 28. These partitions are substantially at right angles to the major axis of the furnace strue.

ture. In alignment with the restricted chamber 27 is the burner 30 similar to burner 19, 'there 1 also being a similar gap 31 between Athe burner and the Wall 28.1 1 These combustion units 1 function similarly.

Burning fuel mixture is introduced, as stated', at 1.

substantial velocity through or from the burner 19 whence it flows toward and into the restricted'chamber 20, for example, past the gap 22,v radiant heat being transmitted there across but without substantial contact of the'burning gases with the product passing through theV fr# VA pressure is set up in the restricted the same, over, around and in contact with the metal sheets, for example.

up an inductive action whereby a portion of the products of combustion is induced into recirculation with the gases flowing into the ref The flow of gases. into thevrestricted Vchamber 20 is such as to`1,set11V the general flow of gases in the furnace toward the charging end thereof. As stated, a similar action obtains -in the opposed adjacent burner unit except that the gases flow from the restricted chamber 27 at right angles to the general flow of the gases through the heating chamber.

At the opposite side of the furnace is provided a similar pair of burner units generally indicated by numerals 33 and 34, being staggered with respect to the rst described units. The function and operation is identical With those previously described. The side walls of the furnace are oiset or inset to accommodate the burners affording easy access to the air supply ducts 35 and gas supply ducts 36 for adjustment or regulation.

The supply of fuel and air is preferably such that pressureis set up in the heating chamber in excess of atmospheric to vprevent infiltration of air. The arrangement of the ports from the respective restricted chambers is such as to assist or enhance the general ow of gases to- Ward and outthe charging end of the heating chamber. With the burner units of the character `described and arranged as described, products of combustion will be successively picked up and recirculated in part as they pass each heating funit, so that some of the gases are repeatedly reheated and'recirculated in their travel through the heating chamber, which contributes markedly to the efficiency of operation. Also with the heat supply means described, re1- atively few burners are required, which makes for flexible and positive control and operation. Also since the sheets or other product being heated, are received at the charging end at a relatively low temperature, they are met by the outflowing gases and encounter an increasing temperature as Athey ilow toward the discharge end of the furnace since, as their temperature increases, they exercise a lesser cooling action upon the products of combustion. Another advantage resides in the fact that the gases during combustion thereof need not be contacted with the product, but only productsf'of combustion which eliminates the hazardous'stratication of air and fuel which might cause oxidization of the sheets. It also reduces the deposit of soot, tarry substances or the like upon the sheets. Forming a continuation with the heating chamber is the cooling chamber V12, there being a restricting transverse wall orY barile 11, previously described, with an opening 11a therethrough to permit the passage of the sheets and `the conveying means.

Leading from the heating chamber, preferably' at the charging end thereof, is the outlet 40 communicating with the extended exterior d uct 41 having the initial portion 41d thereof insulated in the embodiment illustrated..

This 'duct 4l is located above the furnace struc-v elbow or deliverypipe 47 through the top of the' cooling chamber Vinto communication with a transversely extending box 48 having outlet oriflce's148 arranged to deliver jets of gas downwardly upon and along the surfaces of the sheetsjust prior to theirn'discharge from the cooling chamber 12. Extending upwardly from the roof of the cooling chamber adjacent its juncture with the heating chamber is a .plu-

rality of vent pipes or stacks 49, each of which is provided with an adjustable damper 50.

MExtending transverselyfthrough the cooling chamber intermediate its extremities is a plurality of lair pipes 52, terminating at each end in a manifold or header 53-54, these headers being located on the outside of the cooling chamber for convenience. Communicating with the header 53 is the duct 55 also in communication with a motor driven fan 56, which supplies atmospheric air to the header 53, pipes 52 and header 54. From the last, leads a duct 57 and a branch duct 58, the former communieating with the adjacent burner to supply air thereto, and the latter to the opposed burner as illustrated in Fig. 1b. Similarly a branch 59 is provided to supply air to the burners on the opposite side of the heating chamber. Pipes 52 are located above the plane of travel of the sheets in the cooling chamber and in the embodiment shown begin a substantial distance from the restricting wall 11.

A motor 60, speed reducing mechanism 61 and chain 62 together with suitable sprockets furnish driving power for the shaft 63, which carries sprockets 64 for actuation of the conveyer mechanism which may be of any suitable construction.

In the operation of the apparatus described above, metal sheets, for example, are continuously fed into the heating chamber through the charging end thereof where they encounter the outflowing heated gases. They are subjected to an increasing temperature as they travel toward the discharge end of the heating chamber until the desired maximum is reached, as for example, from 175()o F. to 1950" for normalizing. The heated gases of combustion, as stated above, flow rearwardly from the discharge end of the heating chamber toward the charging end thereof, a portion of said gases being picked up in their low past each of the restricted chambers and induced into recirculation with the incoming burning or burned gases for subsequent delivery into the heating chamber proper. From the heating chamber the sheets travel into and through the cooling chamber 12, arriving therein at a maximum temperature. During this travel through the cooling chamber they are submitted to the cooling action of the productsy of combustion which have been extracted from the heating chamber by the exhauster 43 through duct 4l. These cooling gases are delivered downwardly and upon and around these sheets,`

as they are about to pass out of the cooling chamber, so that the ow of coolingv gases is toward the heating chamber. During this flow of the cooling gases they encounter sheets which are of increasing temperature so that the cooling gases are raised in temperature to a maximum where they encounter the sheets at their maximum temperature when they are passed from the heating chamberinto the cooling chamber.

This insures against subjecting the sheets to a marked drop in temperature as they pass from one chamber to the other, while at the same time their temperature is rapidly but more' or less uniformly'reduced to the desired point when they leave the cooling chamber. f

The heated cooling gases, as they approach The pipes 52v conveying air at atmospheric temperature serve materially tov cool or contributeto the maintenance of the cooling gases in relatively cooied lcondition in their fiowin the cooling chamber, Athus contributing` to the rapid cooling ofr the sheets. 'At the same time the heat which is extracted'from the cooling gases by the air inthe pipesf52 serves to `preheat such air prior to itsl delivery to the burners, Whic also adds `to the efficiency of operation as Will be readily'recognized by those skilled in the art. The long travel through the duct 41 permits the substantial radiation of heat from the extracted gases and products of combustion, so that they are very substantially reduced in temperature before they are discharged into the cooling chamber. The operation of the exhauster 43 may be controlled to set up any desirable pressure in the cooling chamber, so that thepressure of the gases in the heating chamber may be balanced or, if desired, overbalanced by the pressure of the cooling gases, so that the latter serve to bailie or obstruct the 110W of heating gases and prevent their substantial entry into the cooling chamber. A damper 41h is provided in duct 41 on suction side of exhauster 43 for control of gas flow through duct 41 and consequent cooling effect. In this wise cooling gases are or may be utilized to initiate and contribute to the rearward flow of the heating gases toward the charging end of the furnace as described above;

An increase in the quantity of the productV being handled by the furnace may require an increase in the cooling action in the cooling chamber, in which event an increased. delivery of cooling gases may be required. In such event, in addition to use of the damper 41'0, the dampers 50 in the vent pipes or stacks 49 may be adjusted to permit the necessary discharge of cooling gases into the atmosphere, thereby permitting an increased delivery of such cooling `gases Without increasing the amount thereof which are recirculated in the cooling chamber.

By the construction and process described above, I am enabledto use a relatively very Vber before discharge thereof to from 800 F. to

1200 F., i. e. to a dull red heat orktherebelow. With `this furnace it is possible-therefore to anneal or normalize materials by first raising them to a suitable high temperature and then oxidizing atmosphere.

"those skilledin the art, particularly as the cost of such structures is more or less proportional to the length thereof. Therefore, the less such structures are utilized for cooling the greater 'capacity and efficiency which will be obtained.

f It will be obvious that my structure and apparatus are susceptible of modification and I do Vnot Wish to be restricted to the forms illustratedY and described, except as I may beV so restricted by the appended claims properly interpreted with respect'to the prior art. i

What I claim is: i.l A furnace of the class described comprising .sop

a heating chamber and a coolingchamber` in alignment-therewith, means to supply heating gases to said heating chamber,v and means to deliver cooled products of'combustion'into said cooling chamber toward said heating chamber, said last named means being constructed and arranged to direct said cooled products of combustion toward said heatingchamber.

2. A furnace of the class described comprising a heating chamber, means to supply heating gases thereto, saidmeans including a burner and a restricted chamber and opposed thereto provided with ports communicating with said heating chamber, said ports being directed at an angie to assist flow of heating gases in said heating chamber toward the charging end thereof.

3. A furnace of the class described comprising a heating chamber and a cooling chamber, means to supply heating gases to said heating chamber, a duct leading 4from said heating cl'iamber `to said cooling chamber, an exhauster associated therewith to extract gases from said heating chamber and deliver them into said cooling chamber, gas deilvery means in said cooling chamber, said duct being in communication therewith, said gas delivery means being constructed and arranged to direct said cooling gases from the discharge end of said cooling chamber toward the charging end thereof.

4. A furnace of the class described comprising a heating chamber and a cooling chamber, means to supply heating gases to said heating chamber, means to deliver gases of combustion from said heating chamber into said cooling chamber adjacent the discharge end thereof, and a vent pipe leading from said cooling chamber adjacent the entrance end thereof.

5. A furnace of the class described comprising a heating chamber having a charging end and a cooling chamber having a discharging end, means to supply heating gases to said heating chamber, a duct leading from said heating chamber adjacent the charging end thereof and leading to said cooling chamber adjacent the discharge end thereof, and means to effect flow of gases from said heating chamber through said duct.

6. A furnace of the class described comprising a heating chamber having a charging end and a cooling chamber having a discharging end,

means to supply heating gases to said heating chamber, a duct leading from said heating chamber adjacent the charging end thereof and vleading to said cooling chamber adjacent the discharge end thereof, said duct being located exteriorly of said furnace whereby said gases will be cooled in travel therethrough.

7. A furnace of the class described comprising a heating vchamber having a charging end and a cooling chamber having a discharging end, means to supply heating gases to said heating chamber, a duct leading from said heating chamber adjacent the charging end thereof and leading to said cooling chamber adjacent the discharge end thereof, and means to effect flow of heating gases from said heating chamber through said duct, said duct being locatedexwith respect to the major axis of said heating chamber. v

9. A furnace of the class described comprising a cooling chamber having a discharge end, means to vdeliver cooled non-oxidizing gases thereinto, said means including spaced orifices constructed and arranged at said discharge end to deliver gases away from said discharge end upon sheets passing therethrough.

HENRY A. DREFFEIN. 

